1. Field of the Invention
The present invention relates to a boehmite having a novel crystal form.
2. Description of the Prior Art
A boehmite is obtainable by the hydrothermal treatment of an aqueous slurry of a boehmite-forming compound such as gibbsite, and has a characteristic crystal form.
FIG. 1 is a schematic view illustrating the crystal form of the conventional boehmite. The boehmite belongs to an orthorhombic system. However, the crystal faces constituting the external form of the crystal are (110), (110) and (001), whereby the interfacial angle between (110) and (110) faces is 76.degree. or 104.degree., and the interfacial angle between (110) and (001) faces and the interfacial angle between (110) and (001) faces are 90.degree.. The a-axis is parallel to (001) face and coincides with a bisector of the interfacial angle of 104.degree. between (110) and (110) faces The b-axis is parallel to (001) face and coincides with a bisector of the interfacial angle of 76.degree. between (110) and (110) faces.
As shown in the scanning electron micrograph (8000 magnifications) of FIG. 2, in the conventional boehmite, (001) crystal face has a diamond or rhombic shape, and (110) and (110) crystal faces are rectangular, and the external form of the entire crystal is monoclinic prismatic.